Door shutter mechanism

ABSTRACT

A stacking mechanism for shutter members of a shutter mechanism, comprising: a rotatable screw with external thread of length L and pitch P 1 ; a plurality of N traveling nuts mounted on the screw, having internal thread of pitch P 1  and external thread of pitch P 2 ,P 1 &gt;P 2 ; an arrester preventing rotation of the nuts within a length L 1  of the screw, while allowing sliding; and a threaded member of pitch P 2  adapted to engage the external thread of the nuts within a length L 2  of the screw. In a first position of the mechanism, the nuts are arranged over the length L 1 . Upon rotation of the screw, the nuts slide along the screw at rate P 1  per 1 turn, transit from L 1  to L 2 , and then slide within the length L 2  at a rate P 2  per 1 turn, thereby achieving reversibly a second position of the mechanism where they are arranged over the length L 2 ,L 2 &lt;L 1.

FIELD OF THE INVENTION

This invention relates to shutter mechanisms for closing openings suchas garage doors and shop windows, and more particularly to shutters witha plurality of parallel bars or blades and motion screw.

BACKGROUND OF THE INVENTION

A common type of shutter mechanism for closing a door opening comprisesa plurality of shutter members such as parallel plates or bladesextending across the opening and movably mounted to opposite sidesthereof. In a closed position of the shutter, the blades lie generallyin the plane of the opening, with touching or overlapping edges, therebyclosing the opening. In an open position of the shutter, the blades areremoved from the opening and may be stacked one over the other orcollapsed face-to-face or rolled in a roll or just drawn away along theceiling or a wall, etc. as the design may be. The transition from closedto open position and back is performed by a motion device that mayemploy pulleys and ropes or chains, scissors lever mechanism, motionscrew, etc. and a motor or manual drive. Another common type of shutterhas a number of parallel bars connected with transverse elements such asdiagonal cross-bars moveable like scissors, or flexible chains, bands,etc. so that these elements obstruct the passage when the parallel barsare in the most spaced position.

For example, U.S. Pat. No. 5,163,494 discloses a sectional doorinstallation comprising a series of horizontal blades mounted with theiropposite ends to scissors linkages. The lowermost linkage is raised orlowered by an endless chain whereby all linkages contract or extendsimultaneously. The blades are mounted to one of the two levers in ascissors pair and turn together with the lever, so that in the mostraised position, the blades are nearly horizontal and are stacked in atight stack under the upper beam of the doorframe.

U.S. Pat. No. 5,469,905 describes a security and hurricane shutter usingblades which are longitudinally pivoted to each other. Every otherpivoting axis is supported in a vertical guide at the two opposing sidesof the door. The shutter can use either pulleys or motion screw thatraises the lowermost blade. Thereby, the whole blade assembly collapseslike accordion towards the upper beam of the door.

U.S. Pat. No. 4,846,244 discloses a window shutter comprising aplurality of horizontal blades, a tilting device for simultaneouslytilting all the blades about their horizontal axes, and a raisingdevice. The blades are mounted on shafts received within channels atopposite sides of the window. The devices for tilting and raising of theblades employ ropes and pulleys like in Venetian blinds.

The usage of motion screws in shutter mechanisms generally allows moreaccurate motion than the usage of ropes or chains. However, the stackingof the blades in known shutter mechanisms requires that only one bladeis engaged with the screw thread thus overloading this blade while theother blades lose the accuracy of motion.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a stackingmechanism for shutter members of a shutter mechanism comprising:

-   -   a rotatable screw with external thread of length L and pitch P1;    -   a plurality of N traveling nuts mounted on the screw, having        internal thread of pitch P1 and external thread of pitch P2        coaxial with the internal thread, P1>P2;    -   an arrester adapted to engage the traveling nuts so as to        prevent their rotation within an axial length L1 of the screw,        while allowing the traveling nuts to slide along the screw;    -   a threaded member with internal thread of pitch P2 adapted to        engage the external thread of the traveling nuts within an axial        length L2 of the screw, the length L2 being adjacent to the        length L1.

The traveling nuts are arranged at intervals W1 _(i), i=1, 2, . . . ,N−1, preferably uniform, within the length L1 in a first position of themechanism. By means of continuous rotation of the screw in onedirection, they can slide along the screw within the length L1 at rateP1 per 1 turn of the screw under the action of the arrester and thethread with pitch P1. The nuts can transit smoothly and reversibly fromL1 to L2, and can slide with rotation along the screw within the lengthL2 at a rate P2 per 1 turn of the traveling nut under the action of thethread with pitch P1 and the thread with pitch P2. The nuts can achievereversibly a second position of the mechanism where they are arranged atintervals W2 _(i), i=1, 2, . . . , N−1 within the length L2, where W2_(i)<W1 _(i) and L2<L1.

Preferably, the arrester is an elongated member, i.e. an L or C-profile,parallel to the screw, and the traveling nuts have a notch engaging theelongated member while the traveling nuts are within the length L1.

Each traveling nut has a connection element mounted for free rotationabout the nut axis and carrying a non-rotating shutter member. Theconnection element is preferably a ring with an inward rim and a radialpin while the nut has an external annular channel adapted to engage theinward rim.

The threaded member has a cutout parallel to the thread axis so that theconnection elements can travel together with the traveling nuts withinthe length L2. The threaded member may be a toothed rack parallel to thescrew, the teeth of the rack constituting thread with pitch P2.

According to another aspect of the present invention, there is provideda shutter mechanism for closing an access aperture, comprising twostacking mechanisms as described above. The stacking mechanisms aredisposed parallel to each other at two opposite sides of the accessaperture with their threaded members at a third side of the aperture(“stacking side”), their N×2 traveling nuts in symmetric disposition,and their screws adapted for synchronous rotation.

The shutter mechanism further comprises a plurality of N shutter membersextending between the stacking mechanisms perpendicularly to theirscrews, each connected to a pair of connection elements. The shuttermembers are distributed over the access aperture in the first positionof the stacking mechanisms, whereby the access aperture is closed. Theshutter members are stacked at the stacking side in the second positionof the stacking mechanisms, whereby the access aperture is opened.

In one embodiment of the present invention, the shutter members are flatrectangular blades with long edges and short edges. Each blade isconnected to the pair of connection elements by its short edges so thatit can swivel about an axis defined by this pair. The blades aredisposed approximately in one common plane in the first position of thestacking mechanisms, and are turned away from this common plane in thesecond position of the stacking mechanisms.

The shutter mechanism further has a pivoting mechanism adapted to swiveleach blade away from the common plane before the traveling nutsconnected to the blade start their transition from the length L1 to thelength L2.

The pivoting mechanism comprises:

-   -   a plurality of N pivoting levers, each one firmly mounted to one        short edge of each blade, generally in a plane perpendicular to        the blade axis, and having a sliding means, e.g. a roller, at a        free end of the lever,    -   a guiding means, e.g. a C-profiled guiding member, extending        parallel to the screws, with a straight portion at least L1        long. The guiding means is adapted to engage for free sliding        the sliding means of each pivoting lever so that each blade        preserves its orientation while traveling along the length L1        with the sliding means engaged in the guiding means,    -   a pivoting means adapted to turn each blade away from said        common plane or to turn each blade into said common plane when a        predetermined traveling nut passes a predetermined position        along the length L.

In a first embodiment of the pivoting mechanism, the pivoting means is acurved portion of the guiding means adapted to catch for a while thefree end of one of the pivoting levers and allow a transverse motion ofthe free end when the respective blade travels past the curved portion,whereby the pivoting lever turns the respective blade.

The pivoting mechanism may be adapted to swivel all blades away fromsaid common plane simultaneously, before the nearest traveling nutstarts its transition from the length L1 to the length L2. In a secondembodiment of the pivoting mechanism, the pivoting means is an assemblycomprising a movable suspension of the guiding member adapted todisplace the guiding member from its initial position transversely tothe screw, while preserving the parallel orientation and the engagementwith the roller. The pivoting assembly further comprises a latchpreventing the displacement of the guiding member when in lockedposition, an actuator engaged with the screw and adapted to unlock andlock the latch in predetermined positions relative to the screw, aplurality of traps associated with the guiding member and adapted tocatch for a while the free end of the lever of each blade when the freeend contacts the trap.

All the above members and elements are disposed in such way that, in theprocess of screw rotation, starting from the first position of thestacking mechanism, the following takes place in succession: thetraveling nuts together with the blades and their levers start movingfrom the length L1 to the length L2, the actuator unlocks the latch andthereby the guiding members, the free ends of the levers aresimultaneously caught by their respective trap means, the movablesuspension displaces the guiding member from its initial position, thelevers turn about their caught free ends and turn the blades away fromthe common plane, the guiding member returns to its initial position,the free ends are released from their trap, the actuator locks the latchand thereby the guiding members, the nuts and the blades in positionaway from the common plane continue moving to the length L2.

In a second embodiment of the present invention—a bar-shuttermechanism—the shutter members are elongated bars. A plurality of movableelements connects each two adjacent bars so as to obstruct the passagebetween the adjacent bars in the first position of the stackingmechanisms (closed position).

In one embodiment of the bar-shutter mechanism, the moveable elementsare short slats with one end rotatably mounted to one bar and a secondend mounted slidingly and rotatably to the adjacent bar. The moveableelements may be also flexible, such as chains, ropes, mesh, textile,elastic sheets, etc.

The stacking mechanism and the shutter mechanism of the presentinvention provide for a very accurate and reliable motion of the shuttermembers. Shutter blades may abut very accurately and tightly in theclosed position of the shutter, while fitting in a compact stack in theopened position of the shutter. The traction force is distributeduniformly and simultaneously to all shutter members. The parts andassemblies of the mechanism are robust and sturdy. The constructionexcludes any possibility of bar or blade misalignment in operation,jamming, locking or seizure of the moving parts.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carriedout in practice, preferred embodiments will now be described, by way ofnon-limiting example only, with reference to the accompanying drawings,in which:

FIGS. 1A, 1B and 1C are external perspective views of a garage door withthe shutter mechanism of the present invention, in three positions.

FIG. 2 is a perspective view of a stacking mechanism according to thepresent invention.

FIG. 3 is an elevation of the stacking mechanism of FIG. 2 as used in adoor shutter.

FIGS. 4A and 4B are a plan view and a sectional elevation respectivelyof a traveling nut according to the present invention.

FIGS. 5A, 5B and 5C are side elevations of the pivoting mechanismaccording to the present invention, in three successive positions.

FIGS. 6A, 6B and 6C are side elevations of another embodiment of thepivoting mechanism, in three successive positions.

FIGS. 7A and 7B are elevations of a bar shutter with the stackingmechanism according to the present invention, in closed and in openedposition, respectively.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1A, 1B and 1C, there are shown externalperspective views of a garage shutter 10 with the shutter mechanism ofthe present invention, the shutter closing an aperture with height L andwidth B. The shutter 10 comprises a plurality of shutter blades 12 withlong edges 14 and short edges 16. In a closed position of the shuttershown in FIG. 1A, the blades 12 lie generally in the plane of theaperture with touching or overlapping long edges 14. In an intermediateposition shown in FIG. 1B, the blades 12 are pivoted about axes parallelto the long edges, providing access for air or light. In an openposition of the shutter shown in FIG. 1C, the plurality of shutterblades are stacked in a neat stack 18 under the upper beam of theshutter. The stack occupies height L2 leaving a free clearance of heightL2.

The stacking mechanism and the construction of the whole shuttermechanism are described in greater detail in the following figures. Withreference to FIG. 2, there is shown a stacking mechanism 20 comprising arotary screw 22 with external thread 24, traveling nuts 26 mountedthereon, an arrester 28, and a threaded member 30 with internal thread32.

The screw 22 has length L and its thread 24 is multi-start thread withpitch P1 (one turn thereof is shown under number 24′).

With reference also to FIGS. 4A and 4B, the traveling nut 26 has a body34 with internal thread 36 of pitch P1 matching the external thread 24and external thread 38 with pitch P2, coaxial with the internal thread.The pitch of the thread P1 is much greater than the pitch P2. Theexternal thread has less than one turn and is formed with two notches 40and 41, leaving a tooth 44 therebetween. The tooth 44 is at the end ofthe thread 38 turn. The nut body 34 also has a cylinder part 46 with anannular channel 48. A connection element formed as a ring 50 with aninward rim 52 is mounted on the nut body 34, the rim engaging thechannel 48 so that the ring can rotate freely about the nut body but cannot be displaced axially. The connection element has a radial pin 54externally attached to the ring 50 which is a part of an articulatejoint with the shutter blades 12.

The arrester 28 is an elongated member with C-like cross-section, oflength L1 disposed parallel to the screw. The sides 56 of the C-sectionengage the notches 40 and 41 of the nut 26, as shown in FIG. 4A.

The treaded member 30 is formed as a tooth rack parallel to the screw22, the teeth constituting the internal thread 32 with pitch P2,matching the thread 38 on the nut 26. The member 32 has length L2 and isdisposed adjacent the arrester 28.

The stacking mechanism 20 operates as follows. With initial position ofthe traveling nut 26′ within the length L1 of the screw, the screw 22starts uniform rotation in one direction. Within the length L1, thetraveling nut 26 is engaged with the arrester 28 by means of the tooth44 and notches 40 and 41 which prevents the i5 rotation of the nut.Therefore, the nut slides along the screw 22 at rate l₁=P1 per 1 turn ofthe screw. When the traveling nut 26 reaches the end of the arrester 28at the boundary between lengths L1 and L2, the tooth 44 disengages fromthe arrester 28. At the same time, the tooth 44 abuts the start of thethread in the threaded member 30 which stops the sliding of the nutalong the screw 22. But now the nut 26 is able to rotate together withthe screw 22, the tooth 44 and the whole thread 38 following theinternal thread 32. Therefore, when within the length L2, the nutperforms a complex motion including rotation with the screw 22 but withangular sliding, and linear translation at rate P2 per 1 turn of thenut. The linear travel 12 of the nut per one turn of the screw is:l ₂=(P1×P2))/(P1+P2)

Upon reverse rotation of the screw, the nut travels back from the lengthL2 to the length L1 with smooth transition. It will be readilyappreciated that if two nuts 26 are positioned initially at a distanceW1 on the length L1 of the screw 22, after both nuts pass over to thelength L2, they will be positioned at a distance W2:W2=(W1×P2)/(P1+P2)

With reference also to FIG. 3, when the stacking mechanism 20 of thepresent invention is used with a plurality of N traveling nuts 26arranged at uniform intervals W1 within the length L1 in a firstposition of the mechanism, then by rotation of the screw, the stackingmechanism will be able to transit reversibly the N traveling nuts into asecond position within the length L2 where the nuts will be “compressed”at uniform intervals W2. It will be appreciated that by selecting thethread pitches P1 and P2, different coefficient of “compression” W1/W2may be achieved.

The stacking mechanism of the present invention is advantageously usedin the shutter mechanism 10 shown externally in FIG. 1. With referencealso to FIG. 3, the shutter mechanism 10 comprises two identicalstacking mechanisms 20 (only one is shown). The stacking mechanisms 20are disposed parallel to each other at two opposite sides of the accessaperture with their threaded members 30 beside the upper beam of thedoorframe. A driving unit 60 is provided for synchronous rotation of thetwo screws 22. The screws carry each N traveling nuts 26A, 26B, etc. insymmetric disposition.

The shutter mechanism 10 further comprises a plurality of N flatrectangular blades 12 with long edges 14, short edges 16 of width W1,and thickness T<W2. The short and long edges of the blades are disposedapproximately in one common plane (the plane of the aperture) in thefirst position of the stacking mechanisms, as shown by blades 12B and12C, whereby the access aperture is closed. The blades are stacked underthe upper beam 59, turned perpendicularly to the common plane, in thesecond position of the stacking mechanisms, as shown by blade 12′,whereby the access aperture is opened.

With reference also to FIGS. 4A and 4B, each traveling nut 26 has a ringconnection element 50 mounted for free rotation about the nut axis. Thering 50 is mounted to the short edge 16 of a blade 12 by means of arotary articulated joint 62 so that each blade can swivel about a bladeaxis defined by two joints 62.

With reference also to FIGS. 5A, 5B and 5C, the shutter mechanismfurther has a pivoting mechanism 70 adapted to swivel each blade awayfrom the common plane before the traveling nuts 26 connected to theblade start their transition from the length L1 to the length L2. Thepivoting mechanism 70 comprises:

a) N pivoting levers 72, each one firmly mounted to one short edge 16 ofeach blade, generally in a plane perpendicular to the blade axis. Eachlever 72 has a roller 74 at its free end 76;

b) A guiding member 78 extending parallel to the screw 22. The guidingmember 78 has a channel profile (C-shaped cross-section) which engagesthe roller of each pivoting lever while the blade is traveling along thescrew;

c) A movable suspension (not shown) of the guiding member allowing theguiding member to be displaced from its initial position transversely tothe screw, while preserving the parallel orientation and the engagementwith the roller;

d) A latch 82 preventing the displacement of the guiding member 78 anddisposed at the lower end of the guiding member;

e) an actuator 84 engaged with the screw 22 and adapted to unlock andlock the latch 82. The actuator 84 is actually a traveling nut 26T thatcarries a finger 85 adapted to engage the latch 82 when moving past thelatch.

f) A plurality of N traps 88 (recesses) disposed on the guiding member78 at intervals W1. The traps 88 are adapted to catch for a while thefree end of the lever of each blade when its roller falls into the trap.

The shutter mechanism 10 operates in the following way. In the firstposition of the stacking mechanism (FIG. 5C and FIG. 3), the blades 12are in the common plane, the travelling nuts are on the length L1 of thescrew, spaced at intervals W1 from each other and engaged in thearrester 28. The levers 72 are orientated upwards, with rollers 74 inthe guiding member 78 which is locked by means of the latch 82. When thedrive 60 starts to rotate the screws 22, the blades 12 start movingupwards. The actuator 84 unlocks the latch 82 and in the next moment therollers 74 are simultaneously caught by the traps 88. The levers 72 pushthe guiding member 78 aside and the movable suspension allows thedisplacement. Thereby, the levers 72 turn about their caught free ends76 and turn the blades 12 away from the common plane (FIG. 5B). In thefollowing travel of the blade, the turning of the levers 72 continue butnow the caught free ends 76 pull the guiding member 78 to its initialposition. The actuator 84 disengages from the latch 82, whereby theguiding member 78 is locked in its initial position. The levers 72therefore quit turning and the rollers 74 are pulled out of the traps.All blades are now pivoted perpendicular to the common plane and in thefurther motion transit from the length L1 to the length L2 and arestacked under the upper beam spaced at interval W2.

During the upward motion, the rollers 74 successively fall into nexttraps 88 but the actuator 84 cannot engage the latch anymore. Therefore,the rollers 74 are pulled out without turning the levers 72.

It should be appreciated that in the reverse (downward) motion, theoperation proceeds exactly in the reverse order.

The pivoting mechanism may be adapted to swivel each blade away from thecommon plane just before its traveling nuts start their transition fromthe length L1 to the length L2. A second embodiment of the pivotingmechanism shown in FIGS. 6A, 6B and 6C comprises the same parts as initems (a) and (b) above but has a simplified turning arrangement,consisting of a single curved portion 90 of the guiding member 78. Thiscurved portion is configured to catch for a while the roller 74 of thelever 72 and to allow a transverse motion of the free end 76 when therespective blade 12 travels past the curved portion. It will beappreciated from the figures, that the pivoting works both ways. In thiscase, the blades preserve their closed position in the common plane allthe way before the length L2.

Another application of the stacking mechanism is shown in FIGS. 7A and7B. A bar-shutter mechanism 100 for the opening 102 comprises twostacking mechanisms 20 disposed parallel to each other at two oppositesides of the access aperture with their threaded members 30 at the upperside of the doorframe. Screws 22, traveling nuts 26, and driving units60 are similar to those described above. The bar-shutter 100 furthercomprises a plurality of N bars or rods 112 with ends mounted to thering connection elements 50 of the traveling nuts 26. Each two adjacentbars are connected by diagonal slats 114. One end of the slat 114 ismounted for rotation on a pin 116 fixed to the upper bar, while theother end is mounted for rotation on a pin 118 fixed to a sleeve 120which is slidingly mounted on the lower bar.

In the first position (FIG. 7A) of the stacking mechanisms 20, the nuts26 and the bars 112 are spaced vertically across the access opening 102,in the range L1. The diagonal slats 114 span the space between each twobars dividing it into small cells and precluding passage of persons. Inthe second position (FIG. 7B) of the stacking mechanisms 20, the nuts 26and the bars 112 are in “compressed” state at the upper side of theaccess opening, in the range L2. The bars 112 are close to each other,the sleeves 120 slide away from the pins 116 and the slats 114 acquirenearly horizontal position. The opening 102 is free for passage.

It would be appreciated that elements which extend between the bars 112may be of various nature, such as flexible chains, ropes, mesh, textile,elastic sheets, etc.

Although a description of specific embodiments has been presented, it iscontemplated that various changes could be made without deviating fromthe scope of the present invention. For example, the present inventioncould be modified and used with gates, windows, awnings, blinds andother kinds of closures where precise motion and reliable closing isneeded. The shutter mechanisms may be mounted with vertical screws, withhorizontal screws and in any orientation of the access aperture plane.

1. A stacking mechanism for shutter members of a shutter mechanismcomprising: a rotatable screw with external thread of length L and pitchP1; a plurality of N traveling nuts mounted on said screw, said nutshaving internal thread of pitch P1 and external thread of pitch P2coaxial with said internal thread, P1>P2; an arrester adapted to engagesaid traveling nuts so as to prevent rotation thereof within an axiallength L1 of said screw, while allowing said traveling nuts to slidealong said screw; a threaded member with internal thread of pitch P2adapted to engage the external thread of said traveling nuts within anaxial length L2 of said screw, said length L2 being adjacent to saidlength L1, said N traveling nuts being arranged at intervals W1 _(i),i=1, 2, . . . , N−1, Is within said length L1 in a first position ofsaid mechanism so that, by means of continuous rotation of said screw inone direction, said traveling nuts can slide along said screw withinsaid length L1 at rate P1 per 1 turn of the screw under the action ofsaid arrester and said thread with pitch P1, can transit smoothly andreversibly from L1 to L2, can slide with rotation along said screwwithin said length L2 at a rate P2 per 1 turn of the traveling nut underthe action of said thread with pitch P1 and said thread with pitch P2,and can achieve reversibly a second position of said mechanism wheresaid N traveling nuts are arranged at intervals W2 _(i), i=1, 2, . . . ,N−1 within said length L2, where W2 _(i)<W1 _(i) and L2 <L1.
 2. Thestacking mechanism according to claim 1, wherein said arrester is anelongated member parallel to said screw, each of said traveling nuts hasa notch parallel to said screw, and said elongated member is received insaid notch while said traveling nuts are within said length L1.
 3. Thestacking mechanism according to claim 2, wherein each traveling nutcomprises a connection element mounted thereon for free rotation andadapted to carry a non-rotating shutter member while traveling withinsaid length L, and said threaded member has a cutout allowing saidconnection element to travel together with the traveling nut thereofwithin said length L2.
 4. The stacking mechanism according to claim 3,wherein said threaded member is a toothed rack parallel to said screw,the teeth of said rack constituting said thread with pitch P2.
 5. Thestacking mechanism according to claim 4, wherein said connection elementcomprises a ring with an inward rim and a radial pin externally attachedto said ring, the respective traveling nut has an annular channel at anexternal surface thereof, and said rim is engaged in said channel sothat the ring can rotate freely about the nut but can not be displacedaxially therefrom while said pin is mounted to said non-rotating shuttermember.
 6. A shutter mechanism for closing an access aperture,comprising two stacking mechanisms according to claim 5 disposedparallel to each other at two opposite sides of said access aperturewith their threaded members at a third side of said access aperture(“stacking side”), with their nuts in symmetric disposition, and theirscrews adapted for synchronous rotation, a plurality of N shuttermembers extending between said stacking mechanisms perpendicularly tothe screws thereof, each connected to a pair of said connectionelements, said shutter members being distributed over said accessaperture in the first position of the stacking mechanisms, whereby saidaccess aperture is closed, and said shutter members being stacked atsaid stacking side in the second position of the stacking mechanisms,whereby said access aperture is opened.
 7. The shutter mechanismaccording to claim 6, wherein said intervals W1 _(i) and W2 _(i) of thestacking mechanisms are uniform.
 8. The shutter mechanism according toclaim 6, wherein said N shutter members are flat rectangular bladeshaving long edges and short edges, each blade is connected by its shortedges to a pair of said connection elements so that said blade canswivel about an axis defined by said pair, said blades are disposedapproximately in one common plane in the first position of the stackingmechanisms and are turned away from said common plane in the secondposition of the stacking mechanisms.
 9. The shutter mechanism accordingto claim 8 further comprising a pivoting mechanism adapted to swiveleach blade away from said common plane before the traveling nutsassociated with each blade start their transition from the length L1 tothe length L2 and to swivel each blade into said common plane after saidtraveling nuts transit from the length L2 into the length L1.
 10. Theshutter mechanism according to claim 9, wherein said pivoting mechanismcomprises: a plurality of N pivoting levers, each one firmly mounted toone short edge of each of said N blades, generally in a planeperpendicular to said blade axis, and having a sliding means at a freeend of the lever, a guiding means extending parallel to said screws,with a straight portion at least L1 long, the guiding means beingadapted to engage for free sliding said sliding means of each pivotinglever so that each blade preserves its orientation while traveling alongthe length L1 with said sliding means engaged in said guiding means. 11.The shutter mechanism according to claim 10, wherein said sliding meansis a roller.
 12. The shutter mechanism according to claim 10, whereinsaid guiding means is a C-shaped profile.
 13. The shutter mechanismaccording to claim 10, wherein said pivoting mechanism further comprisesa pivoting means adapted to turn each blade away from said common planeor into said common plane when a predetermined traveling nut of said Nnuts passes a predetermined position along the length L.
 14. The shuttermechanism according to claim 13, wherein said pivoting means is a curvedportion of said guiding means adapted to catch for a while said free endof said lever and allow a transverse motion of said free end when therespective blade travels past said curved portion, whereby said leverturns the respective blade, said predetermined nut being a nutassociated with said respective blade.
 15. The shutter mechanismaccording to claim 13, wherein said pivoting means is adapted to turnsimultaneously all blades away from said common plane or into saidcommon plane when a predetermined traveling nut of said N nuts passes apredetermined position along the length L.
 16. The shutter mechanismaccording to claim 15, wherein said pivoting means comprises a movablesuspension of said guiding means adapted to displace said guiding meansfrom its initial position transversely to said screw preserving theparallel orientation and the engagement with said sliding means, alocking means preventing the displacement of the guiding means when inlocked position, an actuating means engaged with said screw and adaptedto unlock and lock said locking means in predetermined positionsrelative to said screw, trap means associated with said guiding meansand adapted to catch for a while said free end of said lever of eachblade when said free end contacts said trap means, all the above meansdisposed in such way that, in the process of screw rotation, startingfrom the first position of the stacking mechanism, the following takesplace in succession: the traveling nuts together with the blades andtheir levers start moving from the length L1 to the length L2, theactuator unlocks the locking means and thereby the guiding means, thefree ends of the levers are simultaneously caught by their respectivetrap means, the movable suspension displaces the guiding means from itsinitial position, the levers turn about their caught free ends and turnthe blades away from the common plane, the guiding means return to itsinitial position, the free ends are released from their trap means, theactuator locks the locking means and thereby the guiding means, the nutsand the blades in position away from the common plane continue moving tothe length L2.
 17. The shutter mechanism according to claim 6, whereinsaid N shutter members are elongated bars, the shutter mechanism furthercomprising a plurality of transverse elements movably connecting atleast two adjacent bars of the N elongated bars so as to obstructpassage between said at least two adjacent bars in the first position ofthe stacking mechanisms.
 18. The shutter mechanism according to claim17, wherein said transverse elements are rigid slats with one endmounted rotatably to one of said a least two bars and a second endmounted slidingly and rotatably to the second of said two bars.
 19. Theshutter mechanism according to claim 17, wherein said transverseelements are at least one of the following: chains, ropes, net, mesh,textile, and elastic sheets.
 20. A nut stacking mechanism comprising: arotatable screw with external thread of length L and pitch P1; at leastone traveling nut mounted on said screw, said traveling nut havinginternal thread of pitch P1 and external thread of pitch P2 coaxial withsaid internal thread, P1>P2; an arrester adapted to engage saidtraveling nut so as to prevent rotation thereof within an axial lengthL1 of said screw, while allowing said traveling nut to slide along saidscrew; a threaded member with internal thread of pitch P2 adapted toengage the external thread of said traveling nut within an axial lengthL2 of said screw, said length L2 being adjacent to said length L1, sothat, by means of continuous rotation of said screw in one direction,said traveling nut can slide along said screw within said length L1 atrate P1 per 1 turn of the screw under the action of said arrester andsaid thread with pitch P1, can transit smoothly and reversibly from L1to L2, and can slide with rotation along said screw within said lengthL2 at a rate P2 per 1 turn of the traveling nut under the action of saidthread with pitch P1 and said thread with pitch P2.